This invention relates to flattening twisted veneers as soon as they come from a cutting device.
Veneers as used in this specification are thin sheets of wood used to make plywood and other composite wood products. An example of a specific end use is in wood flooring.
Different techniques for cutting veneers from boards are known. U.S. Pat. No. 5,002,106 to Binder discloses sawing with a bandsaw and slicing with a knife, for example. Various techniques applicable to at least slicing are referred to in the background portion of U.S. Pat. No. 4,516,614 to Grimhall et al. For example, the Grimhall et al. patent refers to a slicing technique in which the board is moved longitudinally across an inclined knife so that the knife slices a veneer of desired thickness from the board. Typically the knife lies obliquely in a horizontal table across which the board is moved. See also U.S. Pat. No. 4,362,197 to Wick et al.
The Wick et al. patent refers to a problem, namely, curling of the veneer, that typically and persistently occurs at least when a veneer is sliced from a board using the aforementioned oblique or inclined knife slicing technique. The process disclosed in the Wick et al. patent includes a step of "soaking the face of the lumber to be sliced in a water bath long enough to eliminate excessive curling of the veneer upon slicing . . . ," (column 1, lines 64-66). Elsewhere the Wick et al. patent states that the quality of the veneer is a function of the type of lumber, the bath temperature, and the residence time in the bath, whereby these factors preferably interrelate such that curling "is only a minor problem" (column 2, lines 18-32).
In the aforementioned '106 patent to Binder (and his related U.S. Pat. No. 5,088,533), Binder did not consider the curling, or warping, problem solved. Binder says, "Furthermore, the quality of the wood sheets thus produced leaves much to be desired, especially since the individual wood sheets leave the cutting device in a greatly warped state, which derives from the fact that the wood sheets cut off from the cut wood plank are carried away obliquely to their original direction of transportation. In the known cutting device, consequently, the problem is posed, which has not been solved to date, of restoring such warped wood sheets into their non-warped, level or flat state at a justifiable expense." (column 2, lines 3-13). Binder's proposed solution is to press the veneers between opposed carpets of wire mesh during drying in a drying apparatus (column 2, lines 33-37; column 3, lines 56-66; and column 6, lines 21-25).
Although the flattening process referred to in the Binder patents may be beneficial, there remains at least the shortcoming of handling difficulties that can arise in transporting the nonflat veneer from the cutting device to the drying apparatus, assuming a drying apparatus is used. That is, when a curled veneer exits a cutting device onto a conveyor as has been the typical practice in the present inventor's experience, the curled veneer generally tends to rock and turn and otherwise shift on the conveyor. This makes handling difficult, and it also causes veneers to be damaged. Such damage causes waste, increases cost and reduces yield (the amount of usable wood per board). This is detrimental both environmentally and financially. Thus, there is the need for an apparatus and method which can immediately flatten veneers as they come directly from the cutting device.